WITHIN A LABORATORY ENVIRONMENT, EMATS HAVE BEEN USED TO CHARACTERIZE DEFECTS IN BOTH FERRITIC AND AUSTENITIC WELDS .

WITHIN A LABORATORY ENVIRONMENT, EMATS HAVE BEEN USED TO CHARACTERIZE DEFECTS IN BOTH FERRITIC AND AUSTENITIC WELDS . THE USE OF SHEAR-HORIZONTAL (SH) WAVES HAS PROVEN PART DEFECTS. FOR FRACTURE MECHANICS EVALUATION OF WELDED STRU STRUCTURES, IT IS PARTICULARLY IMPORTANT TO KNOW THE THROUGHEXTENT OF PLANAR DEFECTS. THIS PROPOSAL SEEKS SUPPORT FOR THE EVALUATION OF A NEW APPROACH TO WELD DEFECT CHARACTERIZATION. IT IS PROPOSED TO USE EMATS GENERATING A COMBINATION OF SH, SHEAR-VERTICAL(SV) AND LONGITUDINAL (L)WAVES TO INTERROGATE THE ENTIRE VOLUME OF A WELD FROM CROWN TO ROOT. EACH EMAT IN THE COMBINATION PROVIDES INFORMATION ABOUT DEFECTS WITHIN A PORTION OF THE WELD; A COMPLETE ASSESSMENT COMES ONLY FROMUSING INFORMATION FROM ALL EMATS. SOME OF THE EMATS USED IN THIS EVALUATION WILL ALSO HAVE THE CAPABILITY OF ELECTRONICALLY SCANNING THE BEAM M ANGLE. THE RESULT OF THIS MULTIPLE INTERROAGATION OF THE WELD FROM DIFFERENT ANGLES IS A MUCH INCREASED RELIABILITY YOF THE ULTRASONIC EVALUATION. (THE PROBABILITY OF MISSING A DEFECT IS VERY SMALL.) SIGNAL PROCESSING METHODS SUCH AS TEMPORAL AVERAGING, SPATIAL AVERAGING, AND SYNTHETIC APERTURE TECHNIQUES WILL BE USED TO INCREASE THE ACCURACY OF DEFECT SIZING, ESPECIALLY DETERMINING THE THROUGH-WALL EXTENT OF A DEFECT. THIS PROJECT WILL ALSO DETERMINE HOW BEST TO IMPLEMENT AUTOMATED ISPECTION METHODS FOR ONE OR MORE COMBINATIONS OF EMATS.